Surface Treatments for Wind Turbine Mountings

Powder coat the pieces. Make sure they will fit into the powder coating shop's oven. A lot of those guys are set up with ovens big enough to take a frame off a race car, street rod or other hobby vehicle. The coating is 10 to 20 mill thickness plastic and can go on most any steel that has had the scale blasted off or is cold finished. Make sure your bolt clearance holes are enough oversize to handle the thickness of the coating. Also mask threaded holes or tap them after the painting. Just remember that if you want to weld on it afterward you have to take an angle grinder and grind off the coating in the weld heat affected zone. You can get just about any color you want. Expect it to be more expensive than galvanizing.

I'm not going to tell you how long powder coating will last on your windmill; but I can tell you it is very popular with guys building land speed racers for the Bonneville Salt Flats.

There are DIY curing paints you can do yourself. There is one consistently popular coating that gives good rust protection. The name escapes me at the moment; but I'm sure one of the other CR-4 folks can tell us what it is. These coatings are expensive but cheaper than powder coating. They usually have limited pot life or air exposure time so best to plan on painting the pieces before you put the windmill together.

Ed Weldon

Epoxy based paints are long-term. The potential for electrical currents exist and could create problems. There are epoxy based paints used on the metal and fibreglass bodies of over-the-road trucks where there is also cyclic flexing.

Unfortunately, all epoxies chalk in sunlight, so do polyurethanes.

Alkyd enamels give good life.

Silicones seem to be good also.

Try an epoxy etch primer on your galvanized steel, then use normal outdoor house paint. (These are formulated with built in UV stabilizers and various other measures to give good outdoor life) Need at least 3 coats.

You will probably get up to 10 years that way.

epoxy paint. 1 or 2 part.

POR 15 plus UV inhibitor

looks similar to powder coat, but can be applied by brush or roller in the field

Before painting steel you will have to give pretreatment. Normally it is seven tank process installed in the factories, but you can get chemical solution which serves same purpose. I will recommend you Epoxy Paint which is normally available in grey or yellow shades. There is painting process to be followed for applying Epoxy Paint. There is Epoxy Primer (Zinc Chromate) available and you will have to apply two coats of this primer.After drying up of primer you can apply two coats of the final paints. Hopefully your paint will last for years.

Suresh Sharma.

DuPont makes a product that used to be Corlar 25, but I think they changed the name. It is primarily a one-coat bridge paint and it is virtually indestructible. It is a 2-part epoxy, very noxious, it can be painted on bare (sandblasted) metal, and it is so viscous that you need a large-orifice spray gun, preferrably airless, to get it on properly. I used this paint on a truck frame during restoration and, when I needed to add some weld-on pieces after painting, I had to grind it off to get to bare metal.

As an afterthought, I have also had steel frames powder-coated for continuous outdoor exposure and they have not held up nearly as well as the Corlar 25-coated members

Small parts are great for powder coating ! Take them to a local bike shop if you have to, they do rims all the time or know where to send it.

Make sure no matter what you do the parts are CLEAN. Sandblast them if necessary.

If you are ready to accept painting often, then I suggest zinc chromate. I personally use it even as a primer. Back in the early 80's I used it on all of my external steel, and it works well. The problem nowadays is it is harder to come by. At that time I was buying it by the gallon and brushing it on or using my sprayer. As of last year, I bought spray cans of it, and was able to get it at grangier. I have gotten it in two colors, lime green and dark red. You will need to use it as a base coat, and you must have a white paint over it to reflect heat not attract it.

I also used on some air conditioning parts that rusted up some rust "remover" and followed it up wit a rust inhibitor.

If you have the money, and are looking for a true long term coating - try thermal spray using Al as the spray metal - this turns "white" (AL Oxide corrosion product) and will give you 40 years or so of coating life. Not cheap - but very effective.

Bingo.

Thank you, Kiwi Bill. You were right twice: (1) solution (2) expense(!)

Sincerely yours,

Minnesotan, ya sure you betcha.

Sir

If you use zinc metallizing instead of hot dip galvanizing, you will provide a great surface for the paint to adhear. Vestas uses this process as a 20 year coating with no maintenance.

Think of an alternate material.

Why not bronze, like the statues that have survived for centuries without re-coating and cleaning.

A 1 kW turbine would not impose substantial drag and so the "tower" could even be a free form shape resembling a tree.

You could powder coat the components of a lattice type tower.

This should have a long life.